Hepatitis is a general term referring to an inflammation of the liver and may be caused by several mechanisms, including infectious agents. Viral hepatitis may be triggered by a variety of different viruses such as hepatitis B, and hepatitis C. Since the development of jaundice is a characteristic feature of liver disease and not just viral hepatitis, a correct diagnosis may only be made by testing patients' blood for the presence of specific anti-viral antibodies.
Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus. It is a major global health problem and the most serious type of viral hepatitis. Hepatitis B virus (HBV) may cause an acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting and abdominal pain, etc. Afflicted individuals may take several months to a year to recover from the symptoms. HBV may also cause a chronic liver infection that may later develop into cirrhosis of the liver or liver cancer, thus putting individuals afflicted with HBV at a high risk of death from cirrhosis of the liver and liver cancer. Worldwide, an estimated two billion people have been infected with HBV, and more than 350 million have chronic (long-term) liver infections. See Previsani et al., “Hepatitis B,” Dept. of Communicable Diseases Surveillance Response, World Health Organization (2002) at page 6.
A vaccine against hepatitis B has been available since 1982. This hepatitis B vaccine is 95% effective in preventing HBV infection and its chronic consequences, including potentially liver cancer. Unfortunately, the potency of this hepatitis B vaccine decreases and wears off over time. In addition, this hepatitis B vaccine is only effective if the person receives this vaccine before the onset HBV infection. In other words, this vaccine cannot be used to treat a person who is already infected with HBV.
Hepatitis C infections are often asymptomatic, but once established, chronic infections may progress to scarring of the liver called fibrosis, as well as advanced scarring (i.e., cirrhosis). In some cases, those with cirrhosis may develop further complications from hepatitis C infections, including hepatocellular carcinoma (HCC). See Previsani et al., “Hepatitis C,” Dept. of Communicable Diseases Surveillance Response, World Health Organization (2002) at pages 3 and 9. Currently there is no effective vaccination against hepatitis C. One reason for no currently effective vaccination against hepatitis C is that this virus may come in many forms and may constantly mutate, thus leading to “swarms” of closely related viral genomic sequences (which are referred to as “quasi-species”).
About 25% of those persons with human immunodeficiency virus (HIV), primarily those who acquired HIV through injection drug use or through a blood transfusion, may also be infected with hepatitis HBV or HCV. Hepatitis B or hepatitis C infections may progress very quickly in HIV-positive people. This co-infection of HIV and hepatitis B or hepatitis C may thus complicate the treatment of affected individuals. For example, people with liver damage due to chronic hepatitis are more likely to experience hepatotoxicity (liver toxicity) related to anti-HIV drugs. In addition, anti-HIV drugs and anti-hepatitis drugs may interact and cause an exacerbation of side effects.
Many experts recommend that HIV should be controlled first before a person begins treatment against viruses such as HBV or HCV. With extremely careful management, people with HIV/HBV or HIV/HCV co-infection may be successfully treated for both diseases. Even so, such careful management treatments may be difficult to carry out because of the need to balance the administration of anti-HIV drugs versus anti-HBV/HCV drugs, e.g., to avoid hepatotoxicity related to anti-HIV drugs, as well as adverse interactions between anti-HIV drugs and anti-HBV/HCV drugs.